Low-pressure and safety cut-in switch



March 2, 1965 s. R. GRIFFIN 3,

LOW-PRESSURE AND SAFETY CUT-IN SWITCH Filed Jan. 23, 1961 EVAPORATOR ULITO COMPRESSOR A I FROM REcEIvER p- E:

COMPRESSOR CONDENSER T0 "nEcE|vER 8 0: IO j E 5 l3 II 9 7 2 I5 is IL] 242 O z E --20 2| '9 ,2o 1' TO I mENsER MOTOR FROM T: F COMPRESSOR :JQL[MENTOR B130 GERALD R. GRIFFIN RATOR REcEIvER United States Patent3,171,264 LflW-PRESSURE AND SAFETY cur-us SWITCH Gerald R. Grifiin, 197Hannasch St, San Antonio, Tex. Filed Earl. 23, 1961, Ser. No. 84,368 4Claims. (Cl. 6Z2ti9) This invention relates generally to temperaturesensitive switches, and is specifically concerned with a safety switchwhich ensures the operation of refrigerators, operating on low pressurecut-in controls, during cold weather,

Refrigerators which are operated by low pressure cut-in controls fail tocut-in if outside temperatures drop below a certain temperature. Undersuch conditions the actual refrigerator temperature will rise above thenormally controlled temperature limits.

It is a primary object of this invention to provide a switch adapted toinitiate operation of a refrigerator cycle when the external temperatureabout the outside of the refrigerator drops to a pre-set temperature.

It is a further object of this invention to provide a gas operated andmechanically actuated switch for refrigeration circuits, ensuring thecontinuing operation of the refrigerator under conditions of lowexternal temperatures.

It is a still further object of this invention to provide a gas operatedelectrical switch responsive to low temperature actuation which is ofsimple constructon, elfective in operation, and may be manufactured atlow cost.

The system of the invention includes a gas filled bulb whichcommunicates with a pressure sensitive bellows through a capillary tube.rigidly secured to a frame, and the opposite end is adapted to actuateone end of a cantilever in response to expansion and contraction of thebellows. The opposite end of the cantilever engages with a flexibleterminal which may be flexed to close a circuit by contact with a secondterminal. The bulb is located near the high pressure side of therefrigerator circuit adjacent the condenser. During operation of therefrigeration cycle, the gas will be warm and the switch of my inventionwill remain in open circuit. However, if the low pressure control failsdue to low outside temperature conditions, the refrigerator gases willbe cooled and likewise the gas in the bulb will cause the switch toactuate and start the cycle. In this way the two control units areinstalled in the same circuit, the temperature sensitive switch of myinvention only operating under cold weather conditions.

Further advantages and objects of this invention will become apparentfrom the following more detailed description of a preferred embodimentthereof, taken in conjunction with the attached drawing whichillustrates diagramatically the components which combine to form theinvention.

Referring now to the drawing wherein a block diagram illustrates arefrigeration system with various conventional components labeled, thenumeral 1 represents a hollow bulb adapted to contain gas. One end ofthe bulb 1 is connected through a capillary tube 2 to the fixed end of apressure sensitive cylindrical bellows 3. The bellows are adapted toexpand and contract axially in response to variable gas pressuresintroduced therein through the capillary tube 2. Mounted externally onthe free end 4 of the bellows 3 is a boss 5 which is adapted to linkwith one end 6 of a fulcrum arm 7. The arm 7 is pivoted on a transverseshaft 8 which is mounted between upstanding bearing tabs 9. The shaft ispositioned relative to the arm 7 such that suitable mechanical advantageis delivered to the opposite end 10 of the arm. An insulating boss 11 ismounted beneath the end 10 of the arm 7.

The end 10 of the arm extends over a terminal board 12 having two spacedelectrical terminals 13 and 14. The

One end of the bellows is 3,171,264 Patented Mar. 2, 1965 terminal 13 iselectrically connected to a flexible conductor arm 15 which terminateswith a contact 16. The remaining terminal 14 connects with a fixedelectrical contact 1'7 through a conductor '18. The terminals connect inopen circuit via the circuit wires 19 and '20 with the electric motorfor driving the compressor. Also in the circuit is the low pressurecut-in control 21 in a line which parallels the contacts 16 and 17.

The bulb 1 is located adjacent the high pressure side of therefrigerator circuit, adjacent the condenser.

It will be appreciated that the dimensions of the above relatedcomponents are a matter of choice. In operation, the unit isincorporated in the refrigerator circuit which is normally controlled bylow pressure cut-in control 21. During conditions of normal externaltemperatures, the refrigeration gases will remain warm and such warmthwill be transmitted to the gas filled bulb 1. The gas, so warmed, willbe expanded causing the bellows to lengthen and maintain the contacts 15and 17 in open circuit. In cold weather however, the gases in therefrigeration cycle become cooled and the pressure sensitive control 21fails to operate. The low temperature will at this time cause acontraction of gas contained in the bulb 1, resulting in a shortening ofthe bellows 3. Such movement causes an anti-clockwise rotation of thefulcrum arm 7, and forces the flexible conductor arm 15 downwardly suchthat the contact 16 is moved into electrical engagement with the contact17, closing the refrigerator motor circuit via wires 16 and 17. When,after adequate operation of the motor and compressor, the gas in bulb 1warms, the bellows 3 will expand to open contacts 16 and 17.

Having described the invention in a preferred form, it will beappreciated that some modifications may be made to the preciseconfiguration, without departing from the scope or spirit of theinvention, as defined by the following claims.

I claim:

1. In a refrigerator system including a condenser, a refrigerator motor,and a low pressure control for operating the refrigerator motor; atemperature responsive means located near the condenser and responsiveto the temperature of the refrigerant in the system; and meanselectrically connected to said motor and operated by'said temperatureresponsive means starting said motor when the temperature responsivemeans reacts to a predetermined low temperature at a time when said lowpressure control may not be operating the refrigerator motor due to lowexternal temperature and stopping said motor when the motor has run fora sufficient period of time to raise the temperature of the temperatureresponsive means.

2. The combination defined in claim 1 in which said temperatureresponsive means comprises a gas filled bulb.

3. The combination defined in claim 2 in which said means operated bysaid temperature responsive means includes a bellows communicating withsaid bulb and lever means operable to close terminal means to energizesaid motor.

4. The combination defined in claim 2 in which said means electricallyconnected to said motor includes contacts made when the temperature ofthe gas in the bulb falls and opened when the temperature of the gas inthe bulb rises.

References Cited in the file of this patent UNITED STATES PATENTS1,101,742 Hays June 30, 1914 1,208,691 Stickle Dec. 12, 1916 1,501,874Wardenburg July 15, 1924 2,191,965 McGrath Feb. 27, 1940 2,195,954Fields Apr. 2, 1940 2,435,530 Candor Feb. 3, 1948

1. IN A REFRIGERATION SYSTEM INCLUDING A CONDENSER, A REFRIGERATORMOTOR, AND A LOW PRESSURE CONTROL FOR OPERATING THE REFRIGERATOR MOTOR;A TEMPERATURE RESPONSIVE MEANS LOCATED NEAR THE CONDENSER AND RESPONSIVETO THE TEMPERATURE OF THE REFRIGERANT IN THE SYSTEM; AND MEANSELECTRICALLY CONNECTED TO SAID MOTOR AND OPERATED BY SAID TEMPERATURERESPONSIVE MEANS STARTING SAID MOTOR WHEN THE TEMPERATURE RESPONSIVEMEANS REACTS TO A PREDETERMINED LOW TEMPERATURE AT A TIME WHEN SAID LOWPRESSURE